1. Field of the Invention
The present invention relates to a powered seat in automobile, and particularly to a method and device for controlling a side support in the powered seat in order to support both sides of an occupant on the seat.
2. Description of Prior Art
Conventionally, there has been available a side support device for supporting both sides of an occupant to prevent him or her against lateral dislocation from a proper seating posture, which has been installed in a driver's seat of an automobile.
The hitherto side support device includes a pair of side support members at the respective lateral sides of a seat back. The side support members at arranged such as to applying a pressure to an upper body part of the occupant on the seat, thereby forcibly restricting the movements of occupant's upper body part.
Use of this side support members to keep pressing both sides of the occupant has been found defective in that the occupant's upper body part can not be moved freely as desired, as a result of which, the occupant becomes unpleasant on such seat and further he or she can not easily get on and out of the automobile. The occupant suffers from an uncomfortable seating and fatigue develops from the restricted seating state. For this reason, normally the side support members are located widely away from each other to provide a free zone to the occupant: Namely, they are located at an open position, and only if the circumstances require the closing of the side support members, an automatic system is effected to cause the drive of a motor to move the side support members to each other at a side support position.
The method for controlling such motion of side support members, for example, is such that a parameter is set for degrees of lateral acceleration and a a standard degree thereof is set for detection of excessive lateral acceleration, and that if the excessive lateral acceleration is detected, the motor is driven to cause the side support members to move to the side support position. For instance, if the lateral acceleration, during driving on a curved road, is applied to the seat at an excessive degree over the standard one, the side support members are automatically moved to the side support position to support the occupant's upper body part. Therefore, the occupant is prevented against undesired dislocation on the seat, and he or she can retain a safe seating.
Such arrangement includes a return of side support members to the open position, which is carried out when the lateral acceleration is lowered below the standard degree and after lapse of a given hold time. However, this automatic opening and closing system of side support members is found defective in that, for instance, when the automobile runs on a winding road in mountainous area, each time of an excessive lateral acceleration is detected, the side support members are moved repeatedly to the side support position, while being returned to the open position each time that the automobile exits the curved parts of road. As a result, such repeated closing and opening of side support members gives an annoying feeling to the occupant and results in making him or her nervous.